Memory devices have a wide variety of uses in modern electronics, including computers, cameras, voice recorders, cell phones, portable storage drives, and similar devices. In addition, many types of memory devices have been developed to affect such uses. Flash memory, for example, is one type of electronic memory media that can store, erase and restore data. Furthermore, flash memory, unlike some types of electronic memory, can retain stored data without continuous electrical power. Flash memory has become a popular device for consumer electronics, due in part to a combination of the high density and low cost of erasable programmable read only memory (EPROM) and electrical erasability introduced with electronically erasable programmable read only memory (EEPROM). In addition to combining these benefits, flash memory is nonvolatile (e.g., flash memory can be removed from a power source without losing stored data). Consequently, it has become a useful and popular mechanism for storing, transporting, sharing and maintaining data.
To further evolve technical capabilities associated with flash memory devices, multiple storage cells have been implemented therewith. Multiple storage cells associated with a flash memory device can typically increase a density and consequently a storage capacity of such device. For example, a dual storage cell enables a single flash memory chip to store two data bits on a single chip. Some side effects can result from multi cell devices, however, as a bit (e.g., represented by a quantized voltage or current level) stored in one cell can affect a voltage or current level, representing a particular bit, of an adjacent cell. In some situations electrical characteristics associated with two different bits of a memory cell can overlap, making those bits difficult to distinguish. Such a condition can produce a memory read error resulting from an inability to distinguish between two or more bit states associated with a cell. To increase reliability and accuracy associated with flash memory, read errors should be reduced or eliminated where possible. To facilitate cell read accuracy, semiconductor suppliers have developed mechanisms to distinguish potentially overlapping cells of such multi-cell devices.